Identification and functional optimization of a novel pteroicidin-like peptide from starry flounder: Structure-activity insights into truncation and tryptophan substitution.

= -11.1 kcal/mol). All peptides exhibited broad-spectrum antimicrobial activity (minimum inhibitory concentration 2.5-10 μM), while selected Trp variants showed enhanced antimicrobial efficiency. The scanning electron microscope confirmed bacterial membrane disruption as the primary mode of action. All analogs rapidly killed the scuticociliate Philasterides dicentrarchi. Hemolysis was concentration-dependent; specifically, the truncated 13-mer retained antimicrobial potency while inducing minimal erythrocyte lysis (< 5% at 50 μM). Overall, rational truncation and strategic Trp substitution modulate efficacy and hemocompatibility, providing a basis for future in vivo evaluation of SFpte-derived analogs as marine-derived bioactive peptide templates for aquaculture applications.